NEXUS – XRT – The concept:

The XRT card is suitable for large NEXUS systems that require complex network topologies and very high channel counts. As is common in NEXUS networks, base devices are connected via duplex fiber optic cables; the XRT plug-in card has twelve standard SFP ports that can be equipped with modules for multimode or singlemode fibers as required.

All twelve available SFP ports transmit the familiar NEXUS protocol with 256 audio channels. Six of the ports can also be operated in high-speed mode and can then handle up to 2048 channels, which means that even the largest capacity requirements can be reliably met. If one of the lines is interrupted, the card automatically uses the second connection. As a special feature, the XRT card supports the use of SFP modules with RJ45 connectors, which enable Ethernet tunneling via the NEXUS network: A simple, helpful option to use the NEXUS infrastructure for otherwise separate Ethernet networks.

NEXUS – XRT – Features:

Tunneling of Ethernet Two of the fiber ports can tunnel Ethernet between two XRT boards when equipped with appropriate SFP modules. More ports can be configured on request. The data rate can be up to 1,000 megabit/s.

Independent routing matrix of 8,448 x 8,448 inputs and outputs The routing capacity has been designed in such a way that all channels of the fiber optic connections and those of the base unit can be included.

Automatic propagation delay compensation for very long fiber optic connections In a NEXUS network, large differences in the distances of the fiber optic connections can occur, among other things, so that the latency that occurs is detected and compensated for by analyzing the word clock phase position.

Six high-speed ports for the transmission of 2,048 audio channels Half of the available fiber ports are designed as high-speed versions and can transmit up to 2048 channels. Together with the routing function, this makes it possible to chain the base devices according to the daisy-chain principle.

Sample-accurate switching in case of failure of redundant connections In both port-based redundancy and card redundancy, signal switching is not audible and can only be detected by a message in the operating software.

Exchangeable standard SFP modules The ports of the XRT card can be equipped with interchangeable SFP fiber optic modules to meet different applications. The modules can be included in the delivery or fitted by the user. Multimode modules are used as standard, which allow a transmission with a range of 500 m. Alternatively, single-modem modules with a range of up to 100Km can also be used.

Redundant configuration of ports possible If two basic devices are connected redundantly, the signals are sent over both lines, so that in the event of an accident the signals can be switched over with sample accuracy and without crackling.

Optionally activatable re-routing in case of failure of non-redundant connections

When optical rerouting is enabled and a fiber optic connection fails or is disconnected, the board automatically searches for another route to the destination. This happens with an interruption of the data stream.

Support of any network topologies The network topologies are freely selectable and, for example, a circular or star-shaped connection structure can be set up.

NEXUS – XRT – Use cases:

Largest audio networks with multiple star networking Star networking is a combination of NEXUS base devices with one or two redundant fiber optic lines to form a central base device that is equipped with an XRT module. Thanks to the integrated matrix with 8448 inputs and outputs, up to 12 other basic devices with all 256 audio channels can be connected. But the six high-speed ports with a transmis- sion capacity of 2048 channels allow the exchange of all possible audio data from eight basic devices and thus the creation of complex network topologies with several star networks that are intercon- nected.

Daisy chaining of Base Devices with a very high number of channels.

The routing function of the XRT allows daisy-chaining of all channels of multiple NEXUS base devices, which was previously limited by the capacity of the active backplane. The XFOC fiber-optic board is in principle a pure I/O board, only with the proprietary STAGETEC protocol. If, due to special requirements, the nature of the NEXUS network structure provides for daisy-chaining, i.e. passing audio channels from one NEXUS base device to the next at a time, a correspondingly large number of the 256 time slots available per NEXUS base device are always occupied. These minimize the maximum input and output channels of the respective Base Devices. In contrast to the otherwise common XFOC, the XRT has its own routing matrix, so that the channel capacity of forwarded audio channels of other base devices is not burdened.